1. Field of the Invention
The present invention relates to an erasing and recovering system for data block on a magnetic tape in a magnetic tape recording and reproducing apparatus.
2. Description of the Related Art
A magnetic tape recording and reproducing apparatus is widely utilized in various fields, particularly, as an external storage device in a data processing system. In a data processing system handling digital data, the data are recorded in the form of data blocks and reproduced for every data block.
In general, a magnetic tape recording and reproducing apparatus has a magnetic tape control system for controlling various parameters, for example, tape speed, head positions for record and reproduction, sensitivity for record and reproduction, etc. Further, the magnetic tape control system performs a recovery process for data error occurring in a write operation of a data block.
Most data error are caused by damage on the magnetic tape. That is, there are various kinds of damage, for example, pin-hole damages and long damage on the magnetic tape. In general, the former does not have an adverse influence when recording a data block, but the latter had a bad effect in the recording and reproducing process of the data blocks. In general, such damages on the magnetic tape occur in the manufacturing process of the magnetic tape.
In the recovery operation for such data error, a magnetic head is returned to the start position and an erase block is written from the same start position. Further, the same data block is written again from the end of the above erase block.